Fix modsuits and defibs (#93373)

## About The Pull Request

Fixes #93359

Caused by #93165

Inventory screen elements were no longer considered reachable, which
broke mousedrop handing on objects that check "is dragging into
inventory slot"

I don't know the best way to fix this yet but I figured the next best
thing would be to make all of these use the `drag_pickup` element, which
skips this reach-ability check

Thus I refactored it slightly to accommodate for items which should
contextually not be drag-pick-up-abble and bam, works like a charm

## Changelog

🆑 Melbert
fix: Dragging defibs and modsuits off your back works again
/🆑

---------

Co-authored-by: ArcaneMusic <41715314+ArcaneMusic@users.noreply.github.com>
Co-authored-by: Xander3359 <66163761+Xander3359@users.noreply.github.com>

code/modules/unit_tests/_unit_tests.dm

@@ -322,6 +322,7 @@
 #include "trauma_granting.dm"
 #include "turf_icons.dm"
 #include "tutorial_sanity.dm"
+#include "unequip_defib.dm"
 #include "unit_test.dm"
 #include "verify_config_tags.dm"
 #include "verify_emoji_names.dm"